Science and technology news

Achilles’ heel of ice shelves is beneath the water, scientists reveal

Posted onSeptember 16, 2013

New research has revealed that more ice leaves Antarctica by melting from the underside of submerged ice shelves than was previously thought, accounting for as much as 90 per cent of ice loss in some areas.

Iceberg production and melting causes 2,800 cubic kilometres of ice to leave the Antarctic ice sheet every year. Most of this is replaced by snowfall but any imbalance contributes to a change in global sea level.

For many decades, experts have believed that the most important process responsible for this huge loss was iceberg calving – the breaking off of chunks of ice at the edge of a glacier.

New research, led by academics at the University of Bristol with colleagues at Utrecht University and the University of California, has used satellite and climate model data to prove that this sub-shelf melting has as large an impact as iceberg calving for Antarctica as a whole and for some areas is far more important.

The findings, published today [15 September] in Nature, are crucial for understanding how the ice sheet interacts with the rest of the climate system and particularly the ocean.

During the last decade, the Antarctic ice-sheet has been losing an increasing amount of its volume. The annual turnover of ice equates to 700 times the four cubic kilometres per year which makes up the entire domestic water supply for the UK.

Researchers found that, for some ice shelves, melting on its underbelly could account for as much as 90 per cent of the mass loss, while for others it was only 10 per cent.

Ice shelves which are thinning already were identified as losing most of their mass from this melting, a finding which will be a good indicator for which ice shelves may be particularly vulnerable to changes in ocean warming in the future.